Ultimately Apple controls the Ligtning spec and they can add capabilities to it as they see fit without having to wait on an external body to ratify. This is super-important for them as the iPhone is the core of their business and they need to be able to iterate as they see fit.
One of the biggest death-knells for Type-C coming to the iPhone is the connector is bigger than Lightning. Apple continues to move towards thinner, lighter with less ports. There's no way they're going to move to a connector that is bigger than their current one.
However on the iPhone and other recent mobile devices they seem to really be behind Lightning.
Is there some reason why the iPhone and MacBook couldn't or shouldn't use the same?